include/net/xdp.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /* include/net/xdp.h
   3  *
   4  * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
   5  */
   6 #ifndef __LINUX_NET_XDP_H__
   7 #define __LINUX_NET_XDP_H__
   8
   9 #include <linux/skbuff.h> /* skb_shared_info */
  10
  11 /**
  12  * DOC: XDP RX-queue information
  13  *
  14  * The XDP RX-queue info (xdp_rxq_info) is associated with the driver
  15  * level RX-ring queues.  It is information that is specific to how
  16  * the driver have configured a given RX-ring queue.
  17  *
  18  * Each xdp_buff frame received in the driver carry a (pointer)
  19  * reference to this xdp_rxq_info structure.  This provides the XDP
  20  * data-path read-access to RX-info for both kernel and bpf-side
  21  * (limited subset).
  22  *
  23  * For now, direct access is only safe while running in NAPI/softirq
  24  * context.  Contents is read-mostly and must not be updated during
  25  * driver NAPI/softirq poll.
  26  *
  27  * The driver usage API is a register and unregister API.
  28  *
  29  * The struct is not directly tied to the XDP prog.  A new XDP prog
  30  * can be attached as long as it doesn't change the underlying
  31  * RX-ring.  If the RX-ring does change significantly, the NIC driver
  32  * naturally need to stop the RX-ring before purging and reallocating
  33  * memory.  In that process the driver MUST call unregistor (which
  34  * also apply for driver shutdown and unload).  The register API is
  35  * also mandatory during RX-ring setup.
  36  */
  37
  38 enum xdp_mem_type {
  39         MEM_TYPE_PAGE_SHARED = 0, /* Split-page refcnt based model */
  40         MEM_TYPE_PAGE_ORDER0,     /* Orig XDP full page model */
  41         MEM_TYPE_PAGE_POOL,
  42         MEM_TYPE_XSK_BUFF_POOL,
  43         MEM_TYPE_MAX,
  44 };
  45
  46 /* XDP flags for ndo_xdp_xmit */
  47 #define XDP_XMIT_FLUSH          (1U << 0)       /* doorbell signal consumer */
  48 #define XDP_XMIT_FLAGS_MASK     XDP_XMIT_FLUSH
  49
  50 struct xdp_mem_info {
  51         u32 type; /* enum xdp_mem_type, but known size type */
  52         u32 id;
  53 };
  54
  55 struct page_pool;
  56
  57 struct xdp_rxq_info {
  58         struct net_device *dev;
  59         u32 queue_index;
  60         u32 reg_state;
  61         struct xdp_mem_info mem;
  62 } ____cacheline_aligned; /* perf critical, avoid false-sharing */
  63
  64 struct xdp_txq_info {
  65         struct net_device *dev;
  66 };
  67
  68 struct xdp_buff {
  69         void *data;
  70         void *data_end;
  71         void *data_meta;
  72         void *data_hard_start;
  73         struct xdp_rxq_info *rxq;
  74         struct xdp_txq_info *txq;
  75         u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
  76 };
  77
  78 /* Reserve memory area at end-of data area.
  79  *
  80  * This macro reserves tailroom in the XDP buffer by limiting the
  81  * XDP/BPF data access to data_hard_end.  Notice same area (and size)
  82  * is used for XDP_PASS, when constructing the SKB via build_skb().
  83  */
  84 #define xdp_data_hard_end(xdp)                          \
  85         ((xdp)->data_hard_start + (xdp)->frame_sz -     \
  86          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
  87
  88 static inline struct skb_shared_info *
  89 xdp_get_shared_info_from_buff(struct xdp_buff *xdp)
  90 {
  91         return (struct skb_shared_info *)xdp_data_hard_end(xdp);
  92 }
  93
  94 struct xdp_frame {
  95         void *data;
  96         u16 len;
  97         u16 headroom;
  98         u32 metasize:8;
  99         u32 frame_sz:24;
 100         /* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
 101          * while mem info is valid on remote CPU.
 102          */
 103         struct xdp_mem_info mem;
 104         struct net_device *dev_rx; /* used by cpumap */
 105 };
 106
 107
 108 static inline struct skb_shared_info *
 109 xdp_get_shared_info_from_frame(struct xdp_frame *frame)
 110 {
 111         void *data_hard_start = frame->data - frame->headroom - sizeof(*frame);
 112
 113         return (struct skb_shared_info *)(data_hard_start + frame->frame_sz -
 114                                 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
 115 }
 116
 117 struct xdp_cpumap_stats {
 118         unsigned int redirect;
 119         unsigned int pass;
 120         unsigned int drop;
 121 };
 122
 123 /* Clear kernel pointers in xdp_frame */
 124 static inline void xdp_scrub_frame(struct xdp_frame *frame)
 125 {
 126         frame->data = NULL;
 127         frame->dev_rx = NULL;
 128 }
 129
 130 /* Avoids inlining WARN macro in fast-path */
 131 void xdp_warn(const char *msg, const char *func, const int line);
 132 #define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
 133
 134 struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
 135
 136 static inline
 137 void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
 138 {
 139         xdp->data_hard_start = frame->data - frame->headroom - sizeof(*frame);
 140         xdp->data = frame->data;
 141         xdp->data_end = frame->data + frame->len;
 142         xdp->data_meta = frame->data - frame->metasize;
 143         xdp->frame_sz = frame->frame_sz;
 144 }
 145
 146 static inline
 147 int xdp_update_frame_from_buff(struct xdp_buff *xdp,
 148                                struct xdp_frame *xdp_frame)
 149 {
 150         int metasize, headroom;
 151
 152         /* Assure headroom is available for storing info */
 153         headroom = xdp->data - xdp->data_hard_start;
 154         metasize = xdp->data - xdp->data_meta;
 155         metasize = metasize > 0 ? metasize : 0;
 156         if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
 157                 return -ENOSPC;
 158
 159         /* Catch if driver didn't reserve tailroom for skb_shared_info */
 160         if (unlikely(xdp->data_end > xdp_data_hard_end(xdp))) {
 161                 XDP_WARN("Driver BUG: missing reserved tailroom");
 162                 return -ENOSPC;
 163         }
 164
 165         xdp_frame->data = xdp->data;
 166         xdp_frame->len  = xdp->data_end - xdp->data;
 167         xdp_frame->headroom = headroom - sizeof(*xdp_frame);
 168         xdp_frame->metasize = metasize;
 169         xdp_frame->frame_sz = xdp->frame_sz;
 170
 171         return 0;
 172 }
 173
 174 /* Convert xdp_buff to xdp_frame */
 175 static inline
 176 struct xdp_frame *xdp_convert_buff_to_frame(struct xdp_buff *xdp)
 177 {
 178         struct xdp_frame *xdp_frame;
 179
 180         if (xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL)
 181                 return xdp_convert_zc_to_xdp_frame(xdp);
 182
 183         /* Store info in top of packet */
 184         xdp_frame = xdp->data_hard_start;
 185         if (unlikely(xdp_update_frame_from_buff(xdp, xdp_frame) < 0))
 186                 return NULL;
 187
 188         /* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
 189         xdp_frame->mem = xdp->rxq->mem;
 190
 191         return xdp_frame;
 192 }
 193
 194 void xdp_return_frame(struct xdp_frame *xdpf);
 195 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
 196 void xdp_return_buff(struct xdp_buff *xdp);
 197
 198 /* When sending xdp_frame into the network stack, then there is no
 199  * return point callback, which is needed to release e.g. DMA-mapping
 200  * resources with page_pool.  Thus, have explicit function to release
 201  * frame resources.
 202  */
 203 void __xdp_release_frame(void *data, struct xdp_mem_info *mem);
 204 static inline void xdp_release_frame(struct xdp_frame *xdpf)
 205 {
 206         struct xdp_mem_info *mem = &xdpf->mem;
 207
 208         /* Curr only page_pool needs this */
 209         if (mem->type == MEM_TYPE_PAGE_POOL)
 210                 __xdp_release_frame(xdpf->data, mem);
 211 }
 212
 213 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
 214                      struct net_device *dev, u32 queue_index);
 215 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
 216 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
 217 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
 218 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 219                                enum xdp_mem_type type, void *allocator);
 220 void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq);
 221
 222 /* Drivers not supporting XDP metadata can use this helper, which
 223  * rejects any room expansion for metadata as a result.
 224  */
 225 static __always_inline void
 226 xdp_set_data_meta_invalid(struct xdp_buff *xdp)
 227 {
 228         xdp->data_meta = xdp->data + 1;
 229 }
 230
 231 static __always_inline bool
 232 xdp_data_meta_unsupported(const struct xdp_buff *xdp)
 233 {
 234         return unlikely(xdp->data_meta > xdp->data);
 235 }
 236
 237 struct xdp_attachment_info {
 238         struct bpf_prog *prog;
 239         u32 flags;
 240 };
 241
 242 struct netdev_bpf;
 243 bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
 244                              struct netdev_bpf *bpf);
 245 void xdp_attachment_setup(struct xdp_attachment_info *info,
 246                           struct netdev_bpf *bpf);
 247
 248 #define DEV_MAP_BULK_SIZE 16
 249
 250 #endif /* __LINUX_NET_XDP_H__ */